Stack smashing with rtaudio

I’ve been recommended to use Csound as an audio mixer with jack, mixing 7 audio inputs down to 5 outputs.
I have used csound many years ago, but I hadn’t used rtaudio (wasn’t available back then!).
In that sense I guess I’m a newbie, though I am familiar with basic Csound stuff.

When I tried the example script I was given I got messages to say my buffer size was not acceptable.
I’m running Jack at 44100sps with 1024samples per period. I tried making the buffer larger (-B 4096) and get stack smashing errors. Also the output suggests it is reading raw shorts from the inputs, but the ports are actually handling samples as 32-bit floats. Any advice on setting things up to get it to work?

An added complication is that I recently moved to using pipewire with the pw-jack add-on. I have been
using jack for a long time, but pipewire may be interacting in some way outside my knowledge.